Data receiving and transmitting system



Feb. 11,1969 R. E. MiLFORD 3,427,585

DATA RECEIVING AND TRANSMITTING SYSTEM Filed May 19, 1965 Sheet of 18 RICHARD E. MILFORD BY ATTORNEY FeB. IT, 1969 R. E. MILFORD 3, 2 3

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x00 5 m0 Qzm .EQIQ GEEK- United States Patent Olfice 3,427,585 DATA RECEIVING AND TRANSMITTING SYSTEM Richard E. Milford, Phoenix, Ariz., assignor to General Electric Company, a corporation of New York Filed May 19, 1965, Ser. No. 456,939 US. Cl. 340-1461 18 Claims Int. Cl. G08b 29/00; H03k 13/32 ABSTRACT OF THE DISCLOSURE A system for sensing data in the form of characters and translating this data'into a sequence of signals representing a character followed by an inverse image of the character in order to make a bit by bit comparison of the character and its inverse image to identify error conditions.

This invention relates to data communications and more particularly to terminal equipment for use at the ends of message networks for receiving and transmitting data to and from business machines which may form a part of an electronic data processing system.

As business enterprises expand geographically to multipoint operations, the transmission of large volumes of data by mail is found to be too slow and by voice impractical. The use of telegraph for data transmission has been satisfactory in many instances; however, the concurrent requirements for data communication and data processing has resulted in the need for an economical terminal which may receive and transmit data automatically over telephone networks.

In many instances, multi-computer sites have been utilized to provide management control of multipoint operations with the resulting benefits of electronic data processing at each of the sites. However, this form of business management involving a plurality of computer sites is expensive and unprofitable if the multipoint operations cannot fully utilize the capacity of the computers. Thus, it is obvious to management of small as well as large multiplant operations that a centralized computer operation is economically desirable if it can be shared with each of the operations at the various sites.

To date, many firms in the business machine, office equipment and communication equipment fields have developed and marketed digital data communication devices. Most operate in conjunction with the common carrier facilities of the telephone and telegraph lines.

It is not enough, however, to merely convert information to digital form and then transmit the information from one site to another. The information in digital form must be transmitted from one business machine to another over the selected transmission line at the baud rate of the line. In addition to the transmission rate and rate capacity of the system, the accuracy of the information transmitted from one business machine to the other must be of a. suflicient high order to warrant reliability. Accuracy is not only a function of the operators performance but in automatic answering terminal equipment, a high order of accuracy of the terminal equipment is necessary for proper functioning of the data communication system. Satisfactory checking system must be provided which will continually check the information being transmitted without disrupting the operation.

System integrity must be maintained if all the component parts and related costs of the data communication system are to be justtified. Good communication systems are much more than just point to point transmission of information. They also must be the best economical means of transferring information from one of many unattended terminals to any one of a number of computer sites. Arrangements must be made for sending and receiving the 3,427,585. Patented Feb. 11, 1969 data without human intervention if the full benefits of data communication systems are to be obtained.

The data communication terminal equipment described comprises communication oriented paper tape terminals. These terminals may transmit information from punched paper tape over 'voice quality half-duplex common carrier or Teletype transmission lines and receive information over the same lines, punching paper tape in accordance with the information received. As utilized herein, the terms information and data are synonymous.

The communication terminal will transmit 5, 6, 7 or 8 level codes at 50 characters per second. It will operate in a half-duplex mode, and by controlling the communication line, alternately send and receive information. Transmission errors are reliably detected when receiving information and the incorrect information is automatically retransmitted. The communication terminal can communicate with another like terminal at the end of the transmission line as well as with associated central processors.

The disclosed communication terminal is further capable of:

(1) Interchanging transmission line data directional flow thereby enabling alternate transmission of blocks of data in both directions;

(2) Performing effective error detection and control by character redundancy transmission;

(3) Retransmitting automatically data received in error;

(4) Permitting the operator to identify an incorrect block of data and use the retransmitted correct block of data in its place;

(5) Operating in an unattended mode; and

(6) Providing protection against voice wrong number calls.

Accordingly, it is an object of this invention to provide a new message accumulation and distribution system.

Another object of this invention is to provide a new data communication paper tape terminal.

A further object of this invention is to provide a bidirectional paper tape transmission system employing novel automatic error detection and correction features.

A still further object of this invention is to provide a new paper tape transmission system employing means for automatically causing the retransmission of data received in error.

A still further object of this invention is to provide a new paper tape transmission system which produces blank tape for the remainder of a block of data after detecting a character in error.

A still further object of this invention is to provide a new information transmission system which identifies an incorrect block of data and utilizes the retransmitted correct block of data in its place.

A still further object of this invention is to provide a new data transmission system which provides alternate transmission of blocks of data in both directions.

Further objects and advantages of the present invention will become apparent to those skilled in the art as the description thereof proceeds.

Brief description of drawings showing information flow in the system of the present invention;

FIG. 3 is a diagrammatic illustration of a 7 bit character frame;

FIG. 4 is a diagrammatic illustration of a 5 bit character frame;

FIG. 5 is a fragment view of an operating tape containing a repetition of one character followed by an End-of- Block code signal;

FIG. 6 is a simplified block diagram of the data sets shown in FIGS. 1 and 2;

FIG. 7 is a schematic illustration of the relay latching arrangement of the data set shown in FIG. 6;

FIG. 8 is a schematic block diagram of the communication control logic shown in FIG. 2;

FIG. 9 is a schematic block diagram of the clock generator portion of the block and bit counter block shown in FIG. 2;

FIG. 10 is a schematic block diagram of the bit counter portion of the clock and bit counter block shown in FIG. 2;

FIG. 11 is a diagrammatic illustration in chart form of the clock and timing signals provided by the clock and bit counter logic shown in FIGS. 2, 9 and 10;

FIG. 12 is a schematic block diagram of a shift register;

FIG. 13 is a simplified block diagram of the reader control logic shown in FIG. 2;

FIG. 14 is a flow chart of the read operation of the structures shown in FIGS. 1 and 2;

FIG. 15 is a diagrammatic illustration of a zero code;

FIG. 16 is a simplified block diagram of the Transmit Serializer flip-flop logic;

FIG. 17 is a diagrammatic illustration chart form of the timing and logic signals involved in a tape reading operation;

FIG. 18 is a fiow chart of the punch operation of the structure shown in FIGS. 1 and 2;

FIG. 19 is a simplified block diagram of the punch control logic shown in FIG. 2;

FIG. 20 is a simplified block diagram of the error punch logic;

FIG. 21 is a schema-tic block diagram of the punch register;

FIG. 22 is a diagrammatic illustration in chart form of the timing and logic signals involved in a punch operation; and

FIG. 23 is a diagrammatic illustration in chart form of the timing signals provided by the punch control logic for the End-of-Data Block recognition.

Glossary and index of signals In order to more readily understand the disclosed invention, the signals provided by the various system circuit elements are tabulated below.

Signals Description of signals DC09 Count 9 in bit counter. DC16 Count 16 in hit counter. DC86 Count 8 or 16 in bit counter. DCOD Carrier Off delayed A second. DCST Clock generator start. DCTl Counter 1 in bit counter. DDSC Reader delayed search complete. DDCR Carrier On leading edge signal. DENA Enable input to punch register. DEND End punch tape mode. DEOB End-of-Block code. DMRK Received Data-mark bit. DOND Carrier On delayed. DPRO Punch in Process. DPUZ Punch zero or blank tape. DSET Serial input to shift register. DSPP Start punch process. DSRE Reset pulse to shift register. DSSR Set Start Search flip-flop. DTCP Tape Read and Clear to Send pulse.

DTCX Tape Read and Clear to Send signal.

DTZR Tape Zero.

DXMO Retransmit.

DXMT Transmit Data to data set.

DZEl Zero code from read amplifiers.

DZER Zero code in shift register.

DZLC Tape Zero and leader.

FC(00-03) Bit counters 1 through 3.

FDPX Half-Duplex Control flip-flop.

FERR Error flip-flop.

FM08 8th Column Memory flip-flop.

FPUT Punch Tape Mode flip-flop.

FPW8 Punch Column 8 flip-flop.

FREV Reader Reverse flip-flop.

FRSD Request to Send flip-flop.

FSH(17) Shift register stages 1 through 7.

FSHE Shift Register Error flip-flop.

FSRH Start Reader Search flip-flop.

FSTP Start Punch Control flip-flop.

FTRD Read Control flip-flop.

FW(0108) Punch Register flip-flops for colums 1 through 8.

FXME Transmit Data Memory flip-flop.

FXMT Transmit Serializer flip-flop.

JCTS Clear to Send from data set.

JDSC Search Complete from reader.

JDRl Data set Ring Line 1.

JDRZ Data set Ring Line 2.

JDNT Energize Interlock 0 fr" l in e switch).

J MDA Data set Receive Data.

JNPT No paper tape signal from punch.

JOND Carrier On signal from data set.

JPUP Punch in Process.

JRS(18) Reader signals for columns 1 through 8.

JREC Reader eject complete.

KINT Interlock relay.

KRIN Ring relay.

QCQl Ungated Clock Generator signal.

QCQ2 Gated Clock Generator signal.

QCXI Start Clock Generator signal.

SCIN Carrier Initiate signal from Request to Send switch.

'I'TS3 Signal from multivibrator.

TTX3 Pulse signal.

DATA COMMUNICATION SYSTEM OPERATION The present invention relates to data communication systems and particularly to terminal equipment for use at the ends of message networks or transmission links such as, for example, telephone lines for interconnecting computers and data accumulation equipment. Since it is believed to be unnecessary to describe the well-known details of these systems to completely describe the invention, block diagrams will be used where possible. However, even though known details will be eliminated, a basic description of the entire system will be presented to enable one skilled in the art to understand the environment in which the present invention is placed.

Accordingly, reference is made to FIG. 1, which shows diagrammatically a data communication system employing data processing facilities. As used herein, data communication means the transmission of information to and from data processing equipment. This includes assembly, sequencing, routing, and selection of such information as is generated at independent remote points of data origination, and the distribution of the processed information to remote output terminals or other data processing equipment. Various means of communicating from one point to another exist today as part of our nations common and private carrier wire lines, cables, cable carriers, radio and microwave facilities.

In the communication system disclosed in FIGS. 1 

